1. Field of Invention
This invention relates to self-propelled submersible suction cleaners, particularly swimming submersible pool suction cleaners. The term "self-propelled" herein means that the suction cleaner is not manually propelled but includes means operated by the flow of water through the suction head to cause propulsion of the device.
2. Description of Background Art
Swimming pool suction cleaners often encounter large objects, such as leaves and twigs, which tend to block the flow of water through the cleaner especially at the entrance to the suction chamber of the suction head. In order to avoid the filter pump from becoming starved and the motor suffering damage, the cleaner device is typically provided with a weir by-pass valve at the coupling of the suction hose to the weir intake for the pump. Such weir, however, also collects floating debris and the weir by-pass valve is likely therefore also to be blocked. In such an event the motor for the pump may well burn out.
Furthermore with the weir by-pass valve at the weir, water will tend to flow via that route to the pump since it provides the least resistance to flow. When the flow rate drops due to clogging of the filter or the strainer at the pump, the diversion of flow via the weir by-pass valve at the weir can cause such drive power loss at the cleaner head such that the latter fails to move at all.